FR-HAUT-L3.2

The rule of twelfths: height at a time, time for a height

FR-HAUT-M3 · Tides · FR-HAUT-M3-A Chart datum and depth sums, the rule of twelfths from a standard port, and tidal streams by coefficient.

The **règle des douzièmes** is the method named in the arrêté. Two questions come up: **what height at a given time**, and **at what time a given height**. Both need the **heure-marée**.

Independent study. xplor is not affiliated with the French maritime administration (DGAMPA), the ENSM, any DDTM or any préfecture maritime, is not an approved bateau-école or training centre, and awards no title, permit, certificate or endorsement. The extension hauturière is obtained only by passing the DDTM's 1h30 paper, in French, on SHOM chart 9999; all chart data in this course are illustrative. AI-drafted content pending subject-matter-expert review.